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186                                  PELTEPHILUS                                 CHAP.

simpler in structure than those which follow. ' The dorsal
vertebrae again are not fused together; the hind-limbs are five-
toed. All the plates of the carapace are arranged in definite
transverse rows; it has been observed, too, that some of the
anterior scutes overlap like fchose of the Armadillos, to which this
animal possesses further likenesses in the exclusion of the
maxillae from the border of the nostril (a Glyptodont character),
and the comparative feebleness of the scutes.

A primitive genus also appears to be JPeltephilus, which is
perhaps rather an Armadillo than a Glyptodon. However, it
comes somewhat between the two, like Propalaeohoplophorus, with
which it may therefore be treated. A most singular feature
of this genus has been mentioned on p. 27 in connexion with
the skull in the Mammalia generally. That is the fact that
a portion of the squamosai surrounding the articular facet for
the lower jaw is separated by a suture from the rest of that
bone, and is therefore obviously suggestive of the quadrate in
the lower Vertebrates. As in certain Armadillos and Glyptodons,
etc., the pterygoids appear in this genus to have taken a share in
the formation of the hard palate. The plates of the carapace were
movable, as is shown by the fact that they sometimes slightly
overlap. In view of the possible origin of the Edentates from
lowly-organised Mammalia, it Is noteworthy that the humerus
has been especially compared to that of the Monotrerne. Pelte-
pliilus differs from other Armadillos in having teeth in the front
of the jaws. The total number of teeth is twenty-eight, i.e. seven
in each half of each jaw.

As already explained, the Old-World Edentates differ from
the New-World forms in having normal dorsal vertebrae, that is
to say, without additional zygapophyses. That negative feature,
however, though combined with the positive fact that both the
Old-World forms feed upon ants, is hardly sufficient to outweigh
the many structural differences which distinguish the Oryctero-
podidae from the Manidae; which will be placed therefore in
different groups. To that containing the Aard Vark, the name
may be applied*